https://source.android.com/ 
/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.media.audiofx;

import android.annotation.IntDef;
import android.media.AudioDeviceInfo;
import android.media.AudioFormat;
import android.media.audiofx.AudioEffect;
import android.util.Log;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.StringTokenizer;



An audio virtualizer is a general name for an effect to spatialize audio channels. The exact
behavior of this effect is dependent on the number of audio input channels and the types and
number of audio output channels of the device. For example, in the case of a stereo input and
stereo headphone output, a stereo widening effect is used when this effect is turned on.

An application creates a Virtualizer object to instantiate and control a virtualizer engine
in the audio framework.

The methods, parameter types and units exposed by the Virtualizer implementation are directly
mapping those defined by the OpenSL ES 1.0.1 Specification (http://www.khronos.org/opensles/)
for the SLVirtualizerItf interface. Please refer to this specification for more details.

To attach the Virtualizer to a particular AudioTrack or MediaPlayer, specify the audio session
ID of this AudioTrack or MediaPlayer when constructing the Virtualizer.

NOTE: attaching a Virtualizer to the global audio output mix by use of session 0 is
deprecated.

See MediaPlayer.getAudioSessionId() for details on audio sessions. 
See AudioEffect class for more details on controlling audio effects. 
/**
 * An audio virtualizer is a general name for an effect to spatialize audio channels. The exact
 * behavior of this effect is dependent on the number of audio input channels and the types and
 * number of audio output channels of the device. For example, in the case of a stereo input and
 * stereo headphone output, a stereo widening effect is used when this effect is turned on.
 * <p>An application creates a Virtualizer object to instantiate and control a virtualizer engine
 * in the audio framework.
 * <p>The methods, parameter types and units exposed by the Virtualizer implementation are directly
 * mapping those defined by the OpenSL ES 1.0.1 Specification (http://www.khronos.org/opensles/)
 * for the SLVirtualizerItf interface. Please refer to this specification for more details.
 * <p>To attach the Virtualizer to a particular AudioTrack or MediaPlayer, specify the audio session
 * ID of this AudioTrack or MediaPlayer when constructing the Virtualizer.
 * <p>NOTE: attaching a Virtualizer to the global audio output mix by use of session 0 is
 * deprecated.
 * <p>See {@link android.media.MediaPlayer#getAudioSessionId()} for details on audio sessions.
 * <p>See {@link android.media.audiofx.AudioEffect} class for more details on controlling
 * audio effects.
 */

public class Virtualizer extends AudioEffect {

    private final static String TAG = "Virtualizer";
    private final static boolean DEBUG = false;

    // These constants must be synchronized with those in
    //        system/media/audio_effects/include/audio_effects/effect_virtualizer.h
    
Is strength parameter supported by virtualizer engine. Parameter ID for getParameter().

/**
     * Is strength parameter supported by virtualizer engine. Parameter ID for getParameter().
     */
    public static final int PARAM_STRENGTH_SUPPORTED = 0;
    
Virtualizer effect strength. Parameter ID for OnParameterChangeListener 
/**
     * Virtualizer effect strength. Parameter ID for
     * {@link android.media.audiofx.Virtualizer.OnParameterChangeListener}
     */
    public static final int PARAM_STRENGTH = 1;
    
@hide
Parameter ID to query the virtual speaker angles for a channel mask / device configuration.
/**
     * @hide
     * Parameter ID to query the virtual speaker angles for a channel mask / device configuration.
     */
    public static final int PARAM_VIRTUAL_SPEAKER_ANGLES = 2;
    
@hide
Parameter ID to force the virtualization mode to be that of a specific device
/**
     * @hide
     * Parameter ID to force the virtualization mode to be that of a specific device
     */
    public static final int PARAM_FORCE_VIRTUALIZATION_MODE = 3;
    
@hide
Parameter ID to query the current virtualization mode.
/**
     * @hide
     * Parameter ID to query the current virtualization mode.
     */
    public static final int PARAM_VIRTUALIZATION_MODE = 4;

    
Indicates if strength parameter is supported by the virtualizer engine

/**
     * Indicates if strength parameter is supported by the virtualizer engine
     */
    private boolean mStrengthSupported = false;

    
Registered listener for parameter changes.

/**
     * Registered listener for parameter changes.
     */
    private OnParameterChangeListener mParamListener = null;

    
Listener used internally to to receive raw parameter change event from AudioEffect super class

/**
     * Listener used internally to to receive raw parameter change event from AudioEffect super class
     */
    private BaseParameterListener mBaseParamListener = null;

    
Lock for access to mParamListener

/**
     * Lock for access to mParamListener
     */
    private final Object mParamListenerLock = new Object();

    
Class constructor.

Params:
  • priority – the priority level requested by the application for controlling the Virtualizer
engine. As the same engine can be shared by several applications, this parameter indicates
how much the requesting application needs control of effect parameters. The normal priority
is 0, above normal is a positive number, below normal a negative number.
  • audioSession –  system wide unique audio session identifier. The Virtualizer will
be attached to the MediaPlayer or AudioTrack in the same audio session.
Throws:
/**
     * Class constructor.
     * @param priority the priority level requested by the application for controlling the Virtualizer
     * engine. As the same engine can be shared by several applications, this parameter indicates
     * how much the requesting application needs control of effect parameters. The normal priority
     * is 0, above normal is a positive number, below normal a negative number.
     * @param audioSession  system wide unique audio session identifier. The Virtualizer will
     * be attached to the MediaPlayer or AudioTrack in the same audio session.
     *
     * @throws java.lang.IllegalStateException
     * @throws java.lang.IllegalArgumentException
     * @throws java.lang.UnsupportedOperationException
     * @throws java.lang.RuntimeException
     */
    public Virtualizer(int priority, int audioSession)
    throws IllegalStateException, IllegalArgumentException,
           UnsupportedOperationException, RuntimeException {
        super(EFFECT_TYPE_VIRTUALIZER, EFFECT_TYPE_NULL, priority, audioSession);

        if (audioSession == 0) {
            Log.w(TAG, "WARNING: attaching a Virtualizer to global output mix is deprecated!");
        }

        int[] value = new int[1];
        checkStatus(getParameter(PARAM_STRENGTH_SUPPORTED, value));
        mStrengthSupported = (value[0] != 0);
    }

    
Indicates whether setting strength is supported. If this method returns false, only one
strength is supported and the setStrength() method always rounds to that value.

Returns:true is strength parameter is supported, false otherwise
/**
     * Indicates whether setting strength is supported. If this method returns false, only one
     * strength is supported and the setStrength() method always rounds to that value.
     * @return true is strength parameter is supported, false otherwise
     */
    public boolean getStrengthSupported() {
       return mStrengthSupported;
    }

    
Sets the strength of the virtualizer effect. If the implementation does not support per mille accuracy for setting the strength, it is allowed to round the given strength to the nearest supported value. You can use the getRoundedStrength() method to query the (possibly rounded) value that was actually set. 
Params:
  • strength – strength of the effect. The valid range for strength strength is [0, 1000],
where 0 per mille designates the mildest effect and 1000 per mille designates the strongest.
Throws:
/**
     * Sets the strength of the virtualizer effect. If the implementation does not support per mille
     * accuracy for setting the strength, it is allowed to round the given strength to the nearest
     * supported value. You can use the {@link #getRoundedStrength()} method to query the
     * (possibly rounded) value that was actually set.
     * @param strength strength of the effect. The valid range for strength strength is [0, 1000],
     * where 0 per mille designates the mildest effect and 1000 per mille designates the strongest.
     * @throws IllegalStateException
     * @throws IllegalArgumentException
     * @throws UnsupportedOperationException
     */
    public void setStrength(short strength)
    throws IllegalStateException, IllegalArgumentException, UnsupportedOperationException {
        checkStatus(setParameter(PARAM_STRENGTH, strength));
    }

    
Gets the current strength of the effect.

Throws:
Returns:the strength of the effect. The valid range for strength is [0, 1000], where 0 per
mille designates the mildest effect and 1000 per mille the strongest
/**
     * Gets the current strength of the effect.
     * @return the strength of the effect. The valid range for strength is [0, 1000], where 0 per
     * mille designates the mildest effect and 1000 per mille the strongest
     * @throws IllegalStateException
     * @throws IllegalArgumentException
     * @throws UnsupportedOperationException
     */
    public short getRoundedStrength()
    throws IllegalStateException, IllegalArgumentException, UnsupportedOperationException {
        short[] value = new short[1];
        checkStatus(getParameter(PARAM_STRENGTH, value));
        return value[0];
    }

    
Checks if a configuration is supported, and query the virtual speaker angles.

Params:
  • inputChannelMask – 
  • deviceType – 
  • angles – if non-null: array in which the angles will be written. If null, no angles
   are returned
Throws:
Returns:true if the combination of channel mask and output device type is supported, false
   otherwise
/**
     * Checks if a configuration is supported, and query the virtual speaker angles.
     * @param inputChannelMask
     * @param deviceType
     * @param angles if non-null: array in which the angles will be written. If null, no angles
     *    are returned
     * @return true if the combination of channel mask and output device type is supported, false
     *    otherwise
     * @throws IllegalStateException
     * @throws IllegalArgumentException
     * @throws UnsupportedOperationException
     */
    private boolean getAnglesInt(int inputChannelMask, int deviceType, int[] angles)
            throws IllegalStateException, IllegalArgumentException, UnsupportedOperationException {
        // parameter check
        if (inputChannelMask == AudioFormat.CHANNEL_INVALID) {
            throw (new IllegalArgumentException(
                    "Virtualizer: illegal CHANNEL_INVALID channel mask"));
        }
        int channelMask = inputChannelMask == AudioFormat.CHANNEL_OUT_DEFAULT ?
                AudioFormat.CHANNEL_OUT_STEREO : inputChannelMask;
        int nbChannels = AudioFormat.channelCountFromOutChannelMask(channelMask);
        if ((angles != null) && (angles.length < (nbChannels * 3))) {
            Log.e(TAG, "Size of array for angles cannot accomodate number of channels in mask ("
                    + nbChannels + ")");
            throw (new IllegalArgumentException(
                    "Virtualizer: array for channel / angle pairs is too small: is " + angles.length
                    + ", should be " + (nbChannels * 3)));
        }

        ByteBuffer paramsConverter = ByteBuffer.allocate(3 /* param + mask + device*/ * 4);
        paramsConverter.order(ByteOrder.nativeOrder());
        paramsConverter.putInt(PARAM_VIRTUAL_SPEAKER_ANGLES);
        // convert channel mask to internal native representation
        paramsConverter.putInt(AudioFormat.convertChannelOutMaskToNativeMask(channelMask));
        // convert Java device type to internal representation
        paramsConverter.putInt(AudioDeviceInfo.convertDeviceTypeToInternalDevice(deviceType));
        // allocate an array to store the results
        byte[] result = new byte[nbChannels * 4/*int to byte*/ * 3/*for mask, azimuth, elevation*/];

        // call into the effect framework
        int status = getParameter(paramsConverter.array(), result);
        if (DEBUG) {
            Log.v(TAG, "getAngles(0x" + Integer.toHexString(inputChannelMask) + ", 0x"
                    + Integer.toHexString(deviceType) + ") returns " + status);
        }

        if (status >= 0) {
            if (angles != null) {
                // convert and copy the results
                ByteBuffer resultConverter = ByteBuffer.wrap(result);
                resultConverter.order(ByteOrder.nativeOrder());
                for (int i = 0 ; i < nbChannels ; i++) {
                    // write the channel mask
                    angles[3 * i] = AudioFormat.convertNativeChannelMaskToOutMask(
                            resultConverter.getInt((i * 4 * 3)));
                    // write the azimuth
                    angles[3 * i + 1] = resultConverter.getInt(i * 4 * 3 + 4);
                    // write the elevation
                    angles[3 * i + 2] = resultConverter.getInt(i * 4 * 3 + 8);
                    if (DEBUG) {
                        Log.v(TAG, "channel 0x" + Integer.toHexString(angles[3*i]).toUpperCase()
                                + " at az=" + angles[3*i+1] + "deg"
                                + " elev="  + angles[3*i+2] + "deg");
                    }
                }
            }
            return true;
        } else if (status == AudioEffect.ERROR_BAD_VALUE) {
            // a BAD_VALUE return from getParameter indicates the configuration is not supported
            // don't throw an exception, just return false
            return false;
        } else {
            // something wrong may have happened
            checkStatus(status);
        }
        // unexpected virtualizer behavior
        Log.e(TAG, "unexpected status code " + status
                + " after getParameter(PARAM_VIRTUAL_SPEAKER_ANGLES)");
        return false;
    }

    
A virtualization mode indicating virtualization processing is not active. See getVirtualizationMode() as one of the possible return value. 
/**
     * A virtualization mode indicating virtualization processing is not active.
     * See {@link #getVirtualizationMode()} as one of the possible return value.
     */
    public static final int VIRTUALIZATION_MODE_OFF = 0;

    
A virtualization mode used to indicate the virtualizer effect must stop forcing the processing to a particular mode in forceVirtualizationMode(int). 
/**
     * A virtualization mode used to indicate the virtualizer effect must stop forcing the
     * processing to a particular mode in {@link #forceVirtualizationMode(int)}.
     */
    public static final int VIRTUALIZATION_MODE_AUTO = 1;
    
A virtualization mode typically used over headphones.
Binaural virtualization describes an audio processing configuration for virtualization
where the left and right channels are respectively reaching the left and right ear of the
user, without also feeding the opposite ear (as is the case when listening over speakers).

Such a mode is therefore meant to be used when audio is playing over stereo wired
headphones or headsets, but also stereo headphones through a wireless A2DP Bluetooth link.

See canVirtualize(int, int) to verify this mode is supported by this Virtualizer. 
/**
     * A virtualization mode typically used over headphones.
     * Binaural virtualization describes an audio processing configuration for virtualization
     * where the left and right channels are respectively reaching the left and right ear of the
     * user, without also feeding the opposite ear (as is the case when listening over speakers).
     * <p>Such a mode is therefore meant to be used when audio is playing over stereo wired
     * headphones or headsets, but also stereo headphones through a wireless A2DP Bluetooth link.
     * <p>See {@link #canVirtualize(int, int)} to verify this mode is supported by this Virtualizer.
     */
    public final static int VIRTUALIZATION_MODE_BINAURAL = 2;

    
A virtualization mode typically used over speakers. Transaural virtualization describes an audio processing configuration that differs from binaural (as described in VIRTUALIZATION_MODE_BINAURAL in that cross-talk is present, i.e. audio played from the left channel also reaches the right ear of the user, and vice-versa. 
When supported, such a mode is therefore meant to be used when audio is playing over the
built-in stereo speakers of a device, if they are featured.

See canVirtualize(int, int) to verify this mode is supported by this Virtualizer. 
/**
     * A virtualization mode typically used over speakers.
     * Transaural virtualization describes an audio processing configuration that differs from
     * binaural (as described in {@link #VIRTUALIZATION_MODE_BINAURAL} in that cross-talk is
     * present, i.e. audio played from the left channel also reaches the right ear of the user,
     * and vice-versa.
     * <p>When supported, such a mode is therefore meant to be used when audio is playing over the
     * built-in stereo speakers of a device, if they are featured.
     * <p>See {@link #canVirtualize(int, int)} to verify this mode is supported by this Virtualizer.
     */
    public final static int VIRTUALIZATION_MODE_TRANSAURAL = 3;

    
@hide
/** @hide */
    @IntDef( {
        VIRTUALIZATION_MODE_BINAURAL,
        VIRTUALIZATION_MODE_TRANSAURAL
    })
    @Retention(RetentionPolicy.SOURCE)
    public @interface VirtualizationMode {}

    
@hide
/** @hide */
    @IntDef( {
        VIRTUALIZATION_MODE_AUTO,
        VIRTUALIZATION_MODE_BINAURAL,
        VIRTUALIZATION_MODE_TRANSAURAL
    })
    @Retention(RetentionPolicy.SOURCE)
    public @interface ForceVirtualizationMode {}

    private static int getDeviceForModeQuery(@VirtualizationMode int virtualizationMode)
            throws IllegalArgumentException {
        switch (virtualizationMode) {
            case VIRTUALIZATION_MODE_BINAURAL:
                return AudioDeviceInfo.TYPE_WIRED_HEADPHONES;
            case VIRTUALIZATION_MODE_TRANSAURAL:
                return AudioDeviceInfo.TYPE_BUILTIN_SPEAKER;
            default:
                throw (new IllegalArgumentException(
                        "Virtualizer: illegal virtualization mode " + virtualizationMode));
        }
    }

    private static int getDeviceForModeForce(@ForceVirtualizationMode int virtualizationMode)
            throws IllegalArgumentException {
        if (virtualizationMode == VIRTUALIZATION_MODE_AUTO) {
            return AudioDeviceInfo.TYPE_UNKNOWN;
        } else {
            return getDeviceForModeQuery(virtualizationMode);
        }
    }

    private static int deviceToMode(int deviceType) {
        switch (deviceType) {
            case AudioDeviceInfo.TYPE_WIRED_HEADSET:
            case AudioDeviceInfo.TYPE_WIRED_HEADPHONES:
            case AudioDeviceInfo.TYPE_BLUETOOTH_SCO:
            case AudioDeviceInfo.TYPE_BUILTIN_EARPIECE:
            case AudioDeviceInfo.TYPE_USB_HEADSET:
                return VIRTUALIZATION_MODE_BINAURAL;
            case AudioDeviceInfo.TYPE_BUILTIN_SPEAKER:
            case AudioDeviceInfo.TYPE_LINE_ANALOG:
            case AudioDeviceInfo.TYPE_LINE_DIGITAL:
            case AudioDeviceInfo.TYPE_BLUETOOTH_A2DP:
            case AudioDeviceInfo.TYPE_HDMI:
            case AudioDeviceInfo.TYPE_HDMI_ARC:
            case AudioDeviceInfo.TYPE_USB_DEVICE:
            case AudioDeviceInfo.TYPE_USB_ACCESSORY:
            case AudioDeviceInfo.TYPE_DOCK:
            case AudioDeviceInfo.TYPE_FM:
            case AudioDeviceInfo.TYPE_AUX_LINE:
                return VIRTUALIZATION_MODE_TRANSAURAL;
            case AudioDeviceInfo.TYPE_UNKNOWN:
            default:
                return VIRTUALIZATION_MODE_OFF;
        }
    }

    
Checks if the combination of a channel mask and virtualization mode is supported by this virtualizer. Some virtualizer implementations may only support binaural processing (i.e. only support headphone output, see VIRTUALIZATION_MODE_BINAURAL), some may support transaural processing (i.e. for speaker output, see VIRTUALIZATION_MODE_TRANSAURAL) for the built-in speakers. Use this method to query the virtualizer implementation capabilities. 
Params:
Throws:
Returns:true if the combination of channel mask and virtualization mode is supported, false
   otherwise.
   
An indication that a certain channel mask is not supported doesn't necessarily mean you cannot play content with that channel mask, it more likely implies the content will be downmixed before being virtualized. For instance a virtualizer that only supports a mask such as AudioFormat.CHANNEL_OUT_STEREO will still be able to process content with a mask of AudioFormat.CHANNEL_OUT_5POINT1, but will downmix the content to stereo first, and then will virtualize, as opposed to virtualizing each channel individually.
/**
     * Checks if the combination of a channel mask and virtualization mode is supported by this
     * virtualizer.
     * Some virtualizer implementations may only support binaural processing (i.e. only support
     * headphone output, see {@link #VIRTUALIZATION_MODE_BINAURAL}), some may support transaural
     * processing (i.e. for speaker output, see {@link #VIRTUALIZATION_MODE_TRANSAURAL}) for the
     * built-in speakers. Use this method to query the virtualizer implementation capabilities.
     * @param inputChannelMask the channel mask of the content to virtualize.
     * @param virtualizationMode the mode for which virtualization processing is to be performed,
     *    one of {@link #VIRTUALIZATION_MODE_BINAURAL}, {@link #VIRTUALIZATION_MODE_TRANSAURAL}.
     * @return true if the combination of channel mask and virtualization mode is supported, false
     *    otherwise.
     *    <br>An indication that a certain channel mask is not supported doesn't necessarily mean
     *    you cannot play content with that channel mask, it more likely implies the content will
     *    be downmixed before being virtualized. For instance a virtualizer that only supports a
     *    mask such as {@link AudioFormat#CHANNEL_OUT_STEREO}
     *    will still be able to process content with a mask of
     *    {@link AudioFormat#CHANNEL_OUT_5POINT1}, but will downmix the content to stereo first, and
     *    then will virtualize, as opposed to virtualizing each channel individually.
     * @throws IllegalStateException
     * @throws IllegalArgumentException
     * @throws UnsupportedOperationException
     */
    public boolean canVirtualize(int inputChannelMask, @VirtualizationMode int virtualizationMode)
            throws IllegalStateException, IllegalArgumentException, UnsupportedOperationException {
        return getAnglesInt(inputChannelMask, getDeviceForModeQuery(virtualizationMode), null);
    }

    
Queries the virtual speaker angles (azimuth and elevation) for a combination of a channel mask and virtualization mode. If the virtualization configuration (mask and mode) is supported (see canVirtualize(int, int), the array angles will contain upon return the definition of each virtual speaker and its azimuth and elevation angles relative to the listener. 
Note that in some virtualizer implementations, the angles may be strength-dependent.

Params:
  • inputChannelMask – the channel mask of the content to virtualize.
  • virtualizationMode – the mode for which virtualization processing is to be performed, one of VIRTUALIZATION_MODE_BINAURAL, VIRTUALIZATION_MODE_TRANSAURAL.
  • angles – a non-null array whose length is 3 times the number of channels in the channel
   mask.
   If the method indicates the configuration is supported, the array will contain upon return
   triplets of values: for each channel i among the channels of the mask:
   
      
     
    • the element at index 3*i in the array contains the speaker identification (e.g. AudioFormat.CHANNEL_OUT_FRONT_LEFT),
      • 
     
    • the element at index 3*i+1 contains its corresponding azimuth angle
         expressed in degrees, where 0 is the direction the listener faces, 180 is behind
         the listener, and -90 is to her/his left,
      • 
     
    • the element at index 3*i+2 contains its corresponding elevation angle
         where +90 is directly above the listener, 0 is the horizontal plane, and -90 is
         directly below the listener.
Throws:
Returns:true if the combination of channel mask and virtualization mode is supported, false
   otherwise.
/**
     * Queries the virtual speaker angles (azimuth and elevation) for a combination of a channel
     * mask and virtualization mode.
     * If the virtualization configuration (mask and mode) is supported (see
     * {@link #canVirtualize(int, int)}, the array angles will contain upon return the
     * definition of each virtual speaker and its azimuth and elevation angles relative to the
     * listener.
     * <br>Note that in some virtualizer implementations, the angles may be strength-dependent.
     * @param inputChannelMask the channel mask of the content to virtualize.
     * @param virtualizationMode the mode for which virtualization processing is to be performed,
     *    one of {@link #VIRTUALIZATION_MODE_BINAURAL}, {@link #VIRTUALIZATION_MODE_TRANSAURAL}.
     * @param angles a non-null array whose length is 3 times the number of channels in the channel
     *    mask.
     *    If the method indicates the configuration is supported, the array will contain upon return
     *    triplets of values: for each channel <code>i</code> among the channels of the mask:
     *    <ul>
     *      <li>the element at index <code>3*i</code> in the array contains the speaker
     *          identification (e.g. {@link AudioFormat#CHANNEL_OUT_FRONT_LEFT}),</li>
     *      <li>the element at index <code>3*i+1</code> contains its corresponding azimuth angle
     *          expressed in degrees, where 0 is the direction the listener faces, 180 is behind
     *          the listener, and -90 is to her/his left,</li>
     *      <li>the element at index <code>3*i+2</code> contains its corresponding elevation angle
     *          where +90 is directly above the listener, 0 is the horizontal plane, and -90 is
     *          directly below the listener.</li>
     * @return true if the combination of channel mask and virtualization mode is supported, false
     *    otherwise.
     * @throws IllegalStateException
     * @throws IllegalArgumentException
     * @throws UnsupportedOperationException
     */
    public boolean getSpeakerAngles(int inputChannelMask,
            @VirtualizationMode int virtualizationMode, int[] angles)
            throws IllegalStateException, IllegalArgumentException, UnsupportedOperationException {
        if (angles == null) {
            throw (new IllegalArgumentException(
                    "Virtualizer: illegal null channel / angle array"));
        }

        return getAnglesInt(inputChannelMask, getDeviceForModeQuery(virtualizationMode), angles);
    }

    
Forces the virtualizer effect to use the given processing mode.
The effect must be enabled for the forced mode to be applied.

Params:
Throws:
Returns:true if the processing mode is supported, and it is successfully set, or
    forcing was successfully disabled, false otherwise.
/**
     * Forces the virtualizer effect to use the given processing mode.
     * The effect must be enabled for the forced mode to be applied.
     * @param virtualizationMode one of {@link #VIRTUALIZATION_MODE_BINAURAL},
     *     {@link #VIRTUALIZATION_MODE_TRANSAURAL} to force a particular processing mode, or
     *     {@value #VIRTUALIZATION_MODE_AUTO} to stop forcing a mode.
     * @return true if the processing mode is supported, and it is successfully set, or
     *     forcing was successfully disabled, false otherwise.
     * @throws IllegalStateException
     * @throws IllegalArgumentException
     * @throws UnsupportedOperationException
     */
    public boolean forceVirtualizationMode(@ForceVirtualizationMode int virtualizationMode)
            throws IllegalStateException, IllegalArgumentException, UnsupportedOperationException {
        // convert Java device type to internal representation
        int deviceType = getDeviceForModeForce(virtualizationMode);
        int internalDevice = AudioDeviceInfo.convertDeviceTypeToInternalDevice(deviceType);

        int status = setParameter(PARAM_FORCE_VIRTUALIZATION_MODE, internalDevice);

        if (status >= 0) {
            return true;
        } else if (status == AudioEffect.ERROR_BAD_VALUE) {
            // a BAD_VALUE return from setParameter indicates the mode can't be forced
            // don't throw an exception, just return false
            return false;
        } else {
            // something wrong may have happened
            checkStatus(status);
        }
        // unexpected virtualizer behavior
        Log.e(TAG, "unexpected status code " + status
                + " after setParameter(PARAM_FORCE_VIRTUALIZATION_MODE)");
        return false;
    }

    
Return the virtualization mode being used, if any.

Throws:
Returns:the virtualization mode being used. If virtualization is not active, the virtualization mode will be VIRTUALIZATION_MODE_OFF. Otherwise the value will be VIRTUALIZATION_MODE_BINAURAL or VIRTUALIZATION_MODE_TRANSAURAL. Virtualization may not be active either because the effect is not enabled or because the current output device is not compatible with this virtualization implementation.
/**
     * Return the virtualization mode being used, if any.
     * @return the virtualization mode being used.
     *     If virtualization is not active, the virtualization mode will be
     *     {@link #VIRTUALIZATION_MODE_OFF}. Otherwise the value will be
     *     {@link #VIRTUALIZATION_MODE_BINAURAL} or {@link #VIRTUALIZATION_MODE_TRANSAURAL}.
     *     Virtualization may not be active either because the effect is not enabled or
     *     because the current output device is not compatible with this virtualization
     *     implementation.
     * @throws IllegalStateException
     * @throws UnsupportedOperationException
     */
    public int getVirtualizationMode()
            throws IllegalStateException, UnsupportedOperationException {
        int[] value = new int[1];
        int status = getParameter(PARAM_VIRTUALIZATION_MODE, value);
        if (status >= 0) {
            return deviceToMode(AudioDeviceInfo.convertInternalDeviceToDeviceType(value[0]));
        } else if (status == AudioEffect.ERROR_BAD_VALUE) {
            return VIRTUALIZATION_MODE_OFF;
        } else {
            // something wrong may have happened
            checkStatus(status);
        }
        // unexpected virtualizer behavior
        Log.e(TAG, "unexpected status code " + status
                + " after getParameter(PARAM_VIRTUALIZATION_MODE)");
        return VIRTUALIZATION_MODE_OFF;
    }

    
The OnParameterChangeListener interface defines a method called by the Virtualizer when a
parameter value has changed.

/**
     * The OnParameterChangeListener interface defines a method called by the Virtualizer when a
     * parameter value has changed.
     */
    public interface OnParameterChangeListener  {
        
Method called when a parameter value has changed. The method is called only if the
parameter was changed by another application having the control of the same
Virtualizer engine.

Params:
  • effect – the Virtualizer on which the interface is registered.
  • status – status of the set parameter operation.
  • param – ID of the modified parameter. See Virtualizer.PARAM_STRENGTH ...
  • value – the new parameter value.
/**
         * Method called when a parameter value has changed. The method is called only if the
         * parameter was changed by another application having the control of the same
         * Virtualizer engine.
         * @param effect the Virtualizer on which the interface is registered.
         * @param status status of the set parameter operation.
         * @param param ID of the modified parameter. See {@link #PARAM_STRENGTH} ...
         * @param value the new parameter value.
         */
        void onParameterChange(Virtualizer effect, int status, int param, short value);
    }

    
Listener used internally to receive unformatted parameter change events from AudioEffect
super class.

/**
     * Listener used internally to receive unformatted parameter change events from AudioEffect
     * super class.
     */
    private class BaseParameterListener implements AudioEffect.OnParameterChangeListener {
        private BaseParameterListener() {

        }
        public void onParameterChange(AudioEffect effect, int status, byte[] param, byte[] value) {
            OnParameterChangeListener l = null;

            synchronized (mParamListenerLock) {
                if (mParamListener != null) {
                    l = mParamListener;
                }
            }
            if (l != null) {
                int p = -1;
                short v = -1;

                if (param.length == 4) {
                    p = byteArrayToInt(param, 0);
                }
                if (value.length == 2) {
                    v = byteArrayToShort(value, 0);
                }
                if (p != -1 && v != -1) {
                    l.onParameterChange(Virtualizer.this, status, p, v);
                }
            }
        }
    }

    
Registers an OnParameterChangeListener interface.

Params:
  • listener – OnParameterChangeListener interface registered
/**
     * Registers an OnParameterChangeListener interface.
     * @param listener OnParameterChangeListener interface registered
     */
    public void setParameterListener(OnParameterChangeListener listener) {
        synchronized (mParamListenerLock) {
            if (mParamListener == null) {
                mParamListener = listener;
                mBaseParamListener = new BaseParameterListener();
                super.setParameterListener(mBaseParamListener);
            }
        }
    }

    
The Settings class regroups all virtualizer parameters. It is used in
conjuntion with getProperties() and setProperties() methods to backup and restore
all parameters in a single call.

/**
     * The Settings class regroups all virtualizer parameters. It is used in
     * conjuntion with getProperties() and setProperties() methods to backup and restore
     * all parameters in a single call.
     */
    public static class Settings {
        public short strength;

        public Settings() {
        }

        
Settings class constructor from a key=value; pairs formatted string. The string is
typically returned by Settings.toString() method.

Throws:
  • IllegalArgumentException – if the string is not correctly formatted.
/**
         * Settings class constructor from a key=value; pairs formatted string. The string is
         * typically returned by Settings.toString() method.
         * @throws IllegalArgumentException if the string is not correctly formatted.
         */
        public Settings(String settings) {
            StringTokenizer st = new StringTokenizer(settings, "=;");
            int tokens = st.countTokens();
            if (st.countTokens() != 3) {
                throw new IllegalArgumentException("settings: " + settings);
            }
            String key = st.nextToken();
            if (!key.equals("Virtualizer")) {
                throw new IllegalArgumentException(
                        "invalid settings for Virtualizer: " + key);
            }
            try {
                key = st.nextToken();
                if (!key.equals("strength")) {
                    throw new IllegalArgumentException("invalid key name: " + key);
                }
                strength = Short.parseShort(st.nextToken());
             } catch (NumberFormatException nfe) {
                throw new IllegalArgumentException("invalid value for key: " + key);
            }
        }

        @Override
        public String toString() {
            String str = new String (
                    "Virtualizer"+
                    ";strength="+Short.toString(strength)
                    );
            return str;
        }
    };


    
Gets the virtualizer properties. This method is useful when a snapshot of current
virtualizer settings must be saved by the application.

Throws:
Returns:a Virtualizer.Settings object containing all current parameters values
/**
     * Gets the virtualizer properties. This method is useful when a snapshot of current
     * virtualizer settings must be saved by the application.
     * @return a Virtualizer.Settings object containing all current parameters values
     * @throws IllegalStateException
     * @throws IllegalArgumentException
     * @throws UnsupportedOperationException
     */
    public Virtualizer.Settings getProperties()
    throws IllegalStateException, IllegalArgumentException, UnsupportedOperationException {
        Settings settings = new Settings();
        short[] value = new short[1];
        checkStatus(getParameter(PARAM_STRENGTH, value));
        settings.strength = value[0];
        return settings;
    }

    
Sets the virtualizer properties. This method is useful when virtualizer settings have to
be applied from a previous backup.

Params:
  • settings – a Virtualizer.Settings object containing the properties to apply
Throws:
/**
     * Sets the virtualizer properties. This method is useful when virtualizer settings have to
     * be applied from a previous backup.
     * @param settings a Virtualizer.Settings object containing the properties to apply
     * @throws IllegalStateException
     * @throws IllegalArgumentException
     * @throws UnsupportedOperationException
     */
    public void setProperties(Virtualizer.Settings settings)
    throws IllegalStateException, IllegalArgumentException, UnsupportedOperationException {
        checkStatus(setParameter(PARAM_STRENGTH, settings.strength));
    }
}